Lee Mantle (December 13, 1851 – November 18, 1934) was a United States Senator from Montana.
Born in Birmingham, England, his mother converted to Mormonism and immigrated to the United States with her children; they settled at Salt Lake City, Utah in 1864. Upon arriving in Utah Territory and facing evidence that Mormon men were practicing polygamy, Mantle's mother came to believe that she had been deceived by the Mormon missionaries and she and her children renounced the LDS Church.
Mantle attended a village school and moved to Idaho Territory in 1870, where he was a telegraph operator and stage agent. He moved to Butte, Montana in 1877 and became agent of the Wells-Fargo Express Co. He established the Inter Mountain, a daily Republican newspaper, in 1881 and served as alderman the same year. He was a member of the Territorial house of representatives in 1882, 1884, and 1888, and served as speaker in 1888; he was mayor of Butte in 1892 and many times chairman of local and State conventions.
Lee Mantle was appointed to the U.S. Senate to fill the vacancy in the term commencing March 4, 1893, caused by the failure of the legislature to elect, but was not seated; he was then elected as a Republican to fill the vacancy and served from January 16, 1895 to March 3, 1899. In 1896, he switched parties and joined the Silver Republican Party. He was an unsuccessful candidate for renomination in 1899, and organized and became chairman of the Silver Republican Party of Montana in 1896, but returned to the Republican Party in 1900. He was manager and part-time editor of the Inter Mountain until 1901 and also engaged in the real estate and mining business. In 1921, he moved to Los Angeles, California and died there in 1934; he was interred in Mount Moriah Cemetery, Butte.